I've been reading The Fall of Berlin and in the book it seems that Stalin was often in contact with his generals and seems to be actively involved in the planning of attacks (especially concerning the acquiring of Nuclear projects in Berlin).
Was Stalin during the course of the war as involved as Hitler? Did he try to micromanage his armies during the course of the war like Hitler or did he have more confidence in his generals? If Stalin took an active approach, are there any examples of mistakes or major military achievements by Stalin?
The short answer is yes. It as if they reversed and switched places. When the Nazis first invaded their neighboring countries in 1939 - 1940 Hitler granted a lot of autonomy to the German general staff of OKW and OKH. Arguably this is why the Germans saw victory after victory in those early years, was because Hitler left running the war to the professionals. However he did set objectives that had to be met, but meeting them was up to the General Staff. Now, on the other hand when the Nazis first invaded the USSR, and the Soviets were suffering heavy casualties, Stalin wanted to be involved in macro and micro planning the war. He forced his generals to make stupid decisions out of fear, that resulted in even more catastrophic loses. The only General who seemed capable of standing up to Stalin, for a while at the begging, was Zhukov. At this same time Hitler was becoming increasingly involved with his military. When things started to slow down in the Smolensk, Yelnya, Kharkov areas in the summer / autumn of 1941, Hitler was increasingly belligerent and increasingly demanding his forces shift south eastwards, instead of continuing on towards Moscow - even though many of his generals argued against this. Stalin was still controlling as ever, but started to slowly allow some autonomy among his Generals. By the time Stalingrad ended in early 1943, Hitler was even more involved with his commanders. He relocated to Wolfs lair and practically controlled ever major movement. Whereas Stalin was becoming more hands off. In the summer of 1944 when Hitler was almost assassinated, he took control of the military. All actions had to go through him. He needed to be briefed daily, if not even hourly by his generals. Stalin on the other hand allowed his Front Generals a lot of leeway, he would say take "XYZ city within a certain time frame" but how you do it is up to you. He also prodded his generals to compete against one another, especially for big prizes such as Berlin.
Edit: However there were cities and things that Stalin wanted, even at the end of the war, that caused major delays and problems for his commanders. Like capturing Breslau and Poznan.